Surgical instrument with input power transducer

ABSTRACT

A surgical instrument in the form of, for example, a two mm needle has an open distal aspiration port for holding tissue to be fractured. An optical fiber extends along the length of the needle and has it&#39;s distal end positioned close to a metal target. Pulses of laser energy are discharged from the distal end of the optical fiber to strike the target. The target acts as a transducer converting the electromagnetic energy to shockwaves that are directed onto tissue in an operating zone adjacent to the aspiration port. The mechanical shockwaves cause the tissue to fracture and the tissue, together with the irrigating fluid is drawn out through an aspirating passageway. A flexible as the needle enhances access to various area where tissue is to be fractured.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of co-pending patentapplications filed by applicant in the United States Patent Office asSer. No. 426,971 on Oct. 25, 1989, entitled Laser Powered SurgicalInstrument; and as Ser. No. 429,141 on Oct. 30, 1989 entitled SurgicalInstrument With Input Power Collector.

BACKGROUND OF THE INVENTION

In general this invention relates to a laser powered surgical instrumentand more particularly to one that provides an efficient and safe meansfor delivering laser energy to tissue for the purpose of operating onthe tissue.

The operating instrument of this invention will be described inconnection with an embodiment adapted to be used in eye surgery andparticularly for cataract removal. However, the invention can beembodied in devices which are adapted to other surgical purposes.

The use of laser energy to perform eye surgery is well known. There area large number of known devices and patents which are relevant to thisart.

One recent patent is the Eichenbaum U.S. Pat. No. 4,698,828 whichcontains an adequate description of the background in this art andcontains a reference to a number of relevant patents. In addition, auseful text that describes both principles and applications of lasersurgery in Ophthalmology is the text The Nd-YAG Laser In Ophthalmologyby Roger F. Steinert and Carmen A. Puliafito, published by W. B.Saunders Company in 1985; ISBN O-7216-1320-9.

The desired parameters for a laser operated surgical device are therequirement of efficiency and small size coupled with avoiding damage toadjacent areas of the tissue being operated on. Enhanced safety for theoperator as well as safety for the patient by minimizing exposure tolaser light are goals of any design for such an instrument. The smallsize provides the advantage of making it possible to operate through avery small incision; a three millimeter incision being a goal incataract surgery. Efficiency of operation serves the advantages of (a)keeping down the overall weight, cost and size of the instrument (b)minimizing the amount of heat or other energy transmitted to adjacenttissue and (c) assuring maximum effect on the tissue to be severed.

Accordingly, the major purpose of this invention is to provide asurgical instrument meeting the above requirements. A related purpose isto provide such an instrument that generates a minimum of heat and hasthe least possible impact on tissue other than the tissue to be operatedon.

Trauma to the patient is reduced by providing minimum size incisions anddelivering the minimum amount of energy to the patient consistent withperforming the operation involved. Trauma is minimized by developing aslittle heat as possible and avoiding loss or scattering of radiantenergy into the patient's tissue other than at the desired site of theoperation. Thus, safety, comfort and minimum trauma consistent withperforming the operation is a goal of any such surgical instrument.

More particularly, from the point of view of minimizing trauma,enhancing safety and minimizing size of surgical instrument, it isimportant to provide as efficient an operating instrument as possible.The efficiency desired is one in which the maximum percentage of inputenergy is delivered to the tissue to be fractured or emulsified.Manifestly, the greater the percentage of input energy that is deliveredto the tissue to be operated on, the less energy will be delivered toother tissue and, in general, the smaller the operating instrument canbe. Thus a goal of this invention is to provide a surgical instrument inwhich a high fraction of energy is delivered to the tissue to beoperated on.

BRIEF DESCRIPTION

In brief, one embodiment of this invention is a surgical instrumentusing neodymium-YAG laser to provide light energy at a wavelength of1,064 nano-meters. This light energy is delivered to the body site inpulses, each pulse having a pulse width of approximately eightnano-seconds.

The surgical instrument is a needle which is essentially an elongatedsmall diameter (approx. 2.0 mm) tubular device. Within the needle, thereis an optical fiber element suitable for carrying the pulses of laserenergy. The distal end of the needle is partly covered by a metal targetand is partly open. The open portion forms an aspiration port. Thedistal end of the fiber is approximately 2.0 mm from the target. Theneedle may have an irrigating passageway along the inner wall of theneedle.

In use, the distal end of the needle is placed adjacent to the tissue tobe removed. A vacuum is applied so that the tissue is pulled against orinto the aspiration port. Laser energy is fed down the fiber as veryshort duration, high repetition rate pulses of energy. This energy isdischarged at the distal end of the fiber and strikes the metal targetto generate shockwaves in the fluid media adjacent to the target. Thisshockwaves fracture the tissue which is being held by the vacuum in thezone adjacent to the port. The tissue thus fractured is aspirated out insmall pieces and the successive pulses of laser energy create successiveshockwaves that fracture off successive bits of tissue. Saline providedby an irrigating tube aids in flushing out the tissue particles thusfractured.

The target reduces the threshold of optical breakdown making it possibleto produce shockwaves with lower energy pulses than without the target.The target is configured and positioned to direct the shockwaves againstthe tissue to be fractured. The target also provides a shield whichprotects surrounding tissue from both laser light and from theshockwaves.

The manner in which the tissue is surgically severed is through theeffect of a series of high energy small duration shockwaves which serveto shatter the tissue on which the shockwaves impinge. It is believedthat this is the primary mechanism by which the device of this inventionachieves its result. The amount of light energy which is converted toheat is sufficiently small so that the heat energy is not believed tohave a significant role in this surgical operation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the distal end of the needle-like probewhich illustrates one embodiment of the device of this invention.

FIG. 2 is a longitudinal cross-section through the FIG. 1 operatinginstrument.

FIG. 3 is a cross-sectional view taken along the plane 3--3 of FIG. 2.

FIG. 4 is a perspective view of the insert used to provide the target inthe FIG. 1 embodiment.

FIG. 5 is a perspective view of the distal end of a second embodiment ofthe device of this invention.

FIG. 6 is a cross-section view taken along the plane 6--6 of FIG. 5.

FIG. 7 is a block diagram illustrating the use of a pulsed lasergenerator is to provide the input energy to the fiber optic element.

FIG. 8 is a longitudinal cross-section of the distal end of a thirdembodiment of the invention illustrating a flexible needle as the probeand in which the irrigating passageway is omitted.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiments shown are similar in many respects and thus the samereference numbers are used for the same part in various embodiments.

As shown in FIGS. 1 through 4, the probe 10 is a needle like distal endof the operating instrument. The probe 10 has a tubular outside wall 12having an outer diameter of for example two millimeters (2 mm) and awall thickness of approximately 0.2 mm. Within the outer tubular wall 12there is an inner tubular wall 14, also having a wall thickness of about0.2 mm. The tube 14 is preferably oval as best seen in FIG. 3. Thepassageway 16 within the inner tubular wall 14 is one through which anirrigating fluid such as a saline solution is administered and isapplied to the tissue being operated on through the sidewall port 18.The passageway 20 between the outer wall 12 and the inner wall 14 is anaspirating passageway 20. Vacuum applied to this aspirating passageway20 serves to draw tissue in through the front port 22.

A titanium insert 24 is wedged into the distal end of the inner tubularwall. FIG. 4 shows the insert 24 for the FIG. 1 embodiment. Thistitanium 24 insert has a target portion 24A which serves, as describedbelow, as a target plate for laser energy. A stem portion 24B has anopening through which an optical fiber element 26 extends.

Tissue which is drawn against the port 22 by vacuum is fractured byshockwaves generated when laser energy emitted from the distal end ofthe optical fiber 26 impinges upon the inner surface of the target 24A.The shockwaves generated are transmitted through the fluid media toimpinge on and fracture the tissue held in the tissue receiving zoneadjacent to the port 22. This fractured tissue, together with theirrigating fluid, is aspirated out through the aspiration passageway 20.

A plastic layer on the outside of the insert 24 may be useful tominimize transmission of shockwaves through the distal end of theinstrument to tissue adjacent the instrument. The plastic material canbe one of those proven to be useable in eyes without serious sideresults such as the plastic used in eye implants. Such plastics usedtoday include the polytetrafluoride resin also known as PTF resin andsold under the trademark Teflon. A plastic sold under the trademarkPerspex can also be used. The plastic layer can be adhered to the distalend of the instrument by known techniques.

The optical fiber 26 has a 300 micro-meter (0.3 mm) diameter coreencased in cladding. The optical fiber 26 together with its cladding isa known type of optical fiber and need not be discussed in detailherein. The distal end of the optical fiber 26 is approximately 2 mmfrom the inner surface of the target 24A.

The irrigating passageway 16 provides liquid at the port 18 at thedistal end 10 of the instrument to irrigate the field of the operation.This liquid also maintains the pressure in the eye where the device isused for cataract surgery. This liquid is necessary to aspirate out thefractured tissue through the aspirating passageway 20.

FIG. 8 illustrates an embodiment where there is no irrigating passagewayin the instrument. Irrigation can be provided by known techniquesthrough use of a standard irrigating tubular instrument. One advantageof the FIG. 8 design is that it makes possible a smaller diameterinstrument than one which requires the irrigating passageway 16.

In operation, pulses of laser energy are transmitted down the opticalfiber 26. The target 24A drops the threshold of optical breakdown andpermits the use of lower energy levels than would otherwise be required.Thus pulses of appropriate energy are emitted from the distal end of theoptical fiber 26 to strike the target 24A and generate mechanicalshockwaves in the fluid media adjacent to the inner surface of thetarget. The shockwaves are directed by the target 24A toward the tissuewhich is held at the port 22 by the vacuum applied to the passageway 20.The shockwaves cause the tissue to fracture into small pieces which arethen sucked out through the aspirating passageway 20.

The target 24A also serves to protect the surrounding tissue from laserenergy. Thus the only tissue exposed to either laser energy orshockwaves is that tissue in the tissue receiving zone adjacent to theport 22. Thus the target functions as a laser light shield.

Because the target is both the target and the shield, its optimumconfiguration will have to be determined by experimentation to providethe optimum trade-off between effective shielding of tissue from laserenergy and effective transmission of shockwaves onto the tissue to befractured.

If particles of fractured tissue get struck in the aspirating passageway20, then by a known technique of reversing the aspirating pump, ametered positive pressure pulse is used to dislodge the stuck particle.

In one embodiment, a neodymium-YAG Q switched laser generator 30 isemployed thereby providing laser energy having a wavelength of 1,064nano-meters. In that embodiment, the laser energy is provided in pulseshaving a duration of eight (8) nano-seconds and a pulse repetition rateof twenty (20) pulses per second. The energy provided is 100milli-joules per second and thus the energy of each pulse is five (5)milli-joules. That particular embodiment is intended for removing acataract in eye surgery.

The embodiment shown in 5 and 6 illustrates an embodiment that ispresently preferred over that shown in FIGS. 1 through 4. This FIG. 5embodiment primarily differs from the FIG. 1 embodiment in that thedistal end of the probe 10 is a plane at an angle of forty-five degrees(45°) to the horizontal and provides a port 22a which more optimallypositions the tissue to receive the shockwaves generated off the innersurface of the titanium insert 24a. The titanium insert 24a has astepped down zone at its proximal end (in the stem portion) to permitbeing fit into the distal end of the stainless steel irrigating tube14a. In addition, the titanium insert 24a is held in place on thestainless steel outer tube 12a by spot welding which creates enough of asurface engagement to hold the titanium insert in place for purposes ofan operating device.

As shown in FIG. 6, the outer tube 12a is preferable elliptical and theinner tube 14a is circular. The value of an elliptical or oval needle 10is that it provides for a more desirable insertion dimension of thewound required to pass the oval operating needle into the eye.

The embodiment shown in FIGS. 5 and 6 represents the most recentlyconstructed and tested embodiment. In the sample of that embodiment thatwas constructed and tested, the tubes 12a and 14b are stainless steeltubes. The following are the approximate dimensions of that sample. Theouter tube 12a has outer dimensions of 2.16 mm by 1.37 mm (85 mils by 54mils) and a wall thickness of 0.1 mm (4.5 mils) The irrigating tube 14ahas a outer diameter of 1.1 mm (43 mils) and a wall thickness of 0.09 mm(3.5 mils). The port 18 has a diameter of 0.69 mm (27 mils) and thedistal edge of the port is located 3.8mm (150 mils) from the distal tipof the probe 10. The titanium insert 24a has a diameter of 1.1 mm (43mils) and is necked down in the stem to be fitted into the irrigatingtube 14a. The necked down zone has a length of 0.89 mm (35 mils) whilethe overall length of the stem of the insert in which this necked downzone is contained is 1.19 mm (47 mils). The opening in the stem of theinsert 24a that accommodates the optical fiber 26 is 0.5 mm (20 mils) soas to provide a slip fit relationship for the fiber 26. This fiber 26has a diameter of 0.45 mm (17 to 18 mils). The neck that connects thedistal triangular target portion with the proximal stem has a width of0.36 mm (14 mils). The distal or front wall of the insert 24a is a planethat is at an angle of forty five degrees (45) to the axis of the probe10. The target wall is perpendicular to the exterior or distal wall ofthe insert.

FIG. 8 shows a design for a flexible needle. A thin wall flexibleplastic tubing 32 such as Teflon has an outer diameter of 2 mm and awall thickness somewhere between 0.1 and 0.5 mm. This tubing 32 is heatshrunk onto the titanium insert 34. The titanium insert 34 contains anecked down zone 36 onto which the tubing 32 is shrunk. The outersurface of the necked down zone 36 preferably has a series of sharpprotuberances which will engage the end of the tubing 32 when the tubingis shrunk onto the necked down zone therefore positively holding thetubing onto the insert. This might prove to be important to assure thatthe shockwaves generated do not drive or pull the insert 34 out of thetubing 32. The FIG. 8 embodiment omits the irrigating passageway therebymaking possible a smaller diameter probe 10. Irrigation is provided by aknown technique using a separate irrigating tube.

Otherwise, the FIG. 8 arrangement is similar to the arrangement shown inFIG. 5. In particular, the optical fiber 26 is mounted in the insert 34and has a distal end spaced from the target face of the insert. Theresult is that shockwaves are reflected down toward a tissue receivingzone inside the instrument and adjacent to the port 36. An opening 38through the insert 34 is made as large as possible in order to provide areasonable opening through which fractured tissue is aspirated out theaspirating passageway 20.

Such a flexible operating instrument will permit ready access by thesurgeon to all portions of the capsular bag in a cataract operation. Thelimit on the radius of curvature of such an instrument will bedetermined by the optical fiber. It is believed that a radius ofcurvature as little as three (3)mm might be achieved in such a design.

A flexible probe might well be controlled by a guide wire similar tothat used in endoscopic controls. This would permit the surgeon to movethe port 36 of the probe to any part of the capsular bag. This wouldallow complete evacuation of the capsular bag through a small openingand allow for refilling of the capsular bag with an optically qualifiedcompound such as silicone.

Although certain embodiments of the invention have been shown, there arevariations in the structure shown which applicant contemplates aspotentially useful. These variations are not necessarily shown. Theywould be understood to one skilled in the art.

For example, the thickness of the titanium target can be adjusted so asto extend the life of the instrument.

The titanium gradually deteriorates in response to each pulsing of thetarget. A given titanium target may operate for about ten thousandpulses. Eight thousand pulses are often required for a single operation.Experience may call for adjusting the thickness of the target to affecttarget life.

As another example, the material of the target might be selected to besome other material that is relatively inactive chemically such as thevarious noble metals.

In addition, the outer surface of the titanium insert 24, 24a, 34 mightbe rounded to assure that any energy transmitted through the target isnot concentrated along a line or at a point.

The use of a separate irrigating tube and the elimination of theirrigating passageway in the probe can be a design feature of a rigidprobe as well as of a flexible probe.

What is claimed is:
 1. A surgical needle for fracturing tissuecomprising:a tubular sidewall having a longitudinal axis and a distalend portion, a laser fiber extending longitudinally to said distal endportion of said sidewall, said laser fiber having a longitudinal axisand a distal end, a target mounted adjacent to said distal end of saidlaser fiber, said target being aligned with said distal end of saidlaser fiber to receive laser energy from said laser fiber, means toproduce laser pulses of sufficient energy to produce optical breakdownat the target material, said distal end portion of said sidewall incommunication with a tissue receiving port and a tissue receiving zoneadjacent to said port, said tissue receiving port and said tissuereceiving zone being radially displaced from said longitudinal axis ofsaid laser fiber, said optical breakdown at said target producingshockwaves that are propagated to said tissue receiving zone, laserenergy from said laser fiber having a path that is displaced from saidtissue receiving zone, and an aspirating passageway extendinglongitudinally within said sidewall and in communication with saidtissue receiving zone.
 2. The surgical needle of claim 1 wherein saidtubular sidewall has a distal endwall and said target comprises at leasta portion of said endwall.
 3. The surgical instrumentation forfracturing tissue comprising:the surgical needle of claim 1, andgeneration means coupled to said laser fiber to provide pulsed laserenergy to said fiber.
 4. The surgical needle of claim 1 wherein saidsidewall is flexible.
 5. The surgical needle of claim 1 furthercomprising:an irrigating passageway within said tubular sidewall, saidtubular sidewall having an irrigating port in communication with saidirrigating passageway, fluid from said irrigating passageway passingthrough said irrigating port to irrigate any tissue at said tissuereceiving port and assist aspiration of fractured tissue through saidaspirating passageway.
 6. The surgical needle of claim 5 wherein saidtubular sidewall has a distal endwall and said target comprises at leasta portion of said endwall.
 7. The surgical instrumentation forfracturing tissue comprising:the surgical needle of claim 5, andgeneration means coupled to said laser fiber to provide pulsed laserenergy to said fiber.
 8. The surgical needle of claim 5 wherein saidsidewall is flexible.
 9. The method of surgically removing tissuecomprising the steps of:drawing tissue into a tissue receiving zone of asurgical needle, providing pulses of laser energy of sufficient energyto produce optical breakdown of the material of a target, directing saidpulses of laser energy along a path displaced from said tissue receivingzone onto said target adjacent to and displaced from said tissuereceiving zone to convert said laser energy into mechanical shockwaves,propagating said mechanical shockwaves to the tissue to be fractured insaid tissue receiving zone and thereby fracturing the tissue, aspiratingthe fractured tissue out of an aspirating passageway in communicationwith said tissue receiving zone, and providing irrigation to an areaoutside said surgical needle to assist said step of aspirating.